In human anatomy, the vermiform appendix (or appendix)
is a blind ended tube connected to the caecum. It develops embryologically from the cecum.

size and location

In adults, the appendix averages 10 cm in length but can range from
2-20 cm. The diameter of the appendix is usually less than 7-8 mm. The longest appendix ever removed was that of a Pakistani
man on June 11, 2003, at Pakistan Institute of Medical Sciences, Islamabad, Pakistan, measuring 23.5 cm (9.2 in) in length.

While the base of the appendix is at a fairly constant location,
the location of the tip of the appendix can vary from being retrocaecal to being in the pelvis to being extraperitoneal. In
most people, the appendix is located at the lower right quadrant of the abdomen. In people with situs inversus, the appendix
may be located in the lower left side.

function

Currently, the function of the appendix, if any, remains controversial
in the field of human physiology. The wall of the appendix, however, contains lymphatic tissue that is part of the immune
system for making antibodies.

Hypothesized functions for the appendix include lymphatic, exocrine,
endocrine, and neuromuscular functions. However, most physicians and scientiss believe the appendix lacks significant function,
and that it exists primarily as a vestigial remnant of the larger cellulose-digesting cecum found in our herbivorous ancestors.
Some people note, however, that the pineal gland which only recently (around 1960) has been found to produce important chemicals
like melatonin was once considered a vestigial remnant as well.

There have been cases of people who have been found, usually on
laparoscopy or laparotomy, to have a congenital absence of their appendix. There have been no reports of impaired immune or
gastrointestinal function.

diseases

The most common diseases of the appendix (in humans) are appendicitis
and carcinoid.